False Widow Spiders On Rise, Experts Raise Warning Over Dangerous Bites

by : Emily Brown on :
False Widow Spiders On Rise, Experts Raise Warning Over Dangerous BitesStu's Images (CC-BY-4.0)/PA Images

Experts have warned about the possible severity of false widow spider bites as the species has increased in numbers and become one of the most common found in and around urban habitats. 

In a study published in the international medical journal Clinical Toxicology, scientists from NUI Galway looked into the threat posed by the Noble False Widow spider; a topic that has reportedly been debated among spider and healthcare specialists for some time.


The symptoms of a venomous bite can range from causing mild discomfort and swelling to unbearable pain and intense swelling, with the study confirming that some victims of false widow spider bites experience symptoms similar to true black widow spiders.

To ensure the study was accurate, scientists only compiled envenomation cases where they had a clear identification of the spider responsible for the bite, Dr. John Dunbar, Postdoctoral Researcher at the Venom Systems Lab at NUI Galway and lead author of the study, explained.

Victims of bites have been known to experience tremors, reduced or elevated blood pressure, nausea and impaired mobility, and researchers have noted that severe cases require hospitalisation.


The species originated from Madeira and the Canary Islands, but has the potential to become one of the world’s most invasive species of spider as it increases in numbers.

It was first documented in Britain more than 140 years ago, however it has recently expanded its range and density to become one of the most common species of spiders found in and around urban habitats in parts of Ireland and Britain.

False Widow Spider (Stu's Images (CC-BY-4.0))Stu's Images (CC-BY-4.0)

Analysis of the distribution of bites determined they most frequently occur in and around the home, with an even more unnerving finding revealing 88% of bites occurred when the victim was either asleep in bed or when the spider was trapped in clothing.


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It’s not clear what prompted the boom of false widow spiders, but while scientists have ruled out climate change they have suggested a genetic mutation within the species may have made them more adaptable to new environments.

False widows are also thought to have benefitted from increasing global connectivity, travelling across the world in containers and crates to spread throughout Europe, North Africa, West Asia and parts of North and South America.

False Widow Spider (Stu's Images (CC-BY-4.0))Stu's Images (CC-BY-4.0)

Per phys.org, senior author Dr. Michel Dugon, Head of the Venom Systems Lab at NUI Galway, said:


In addition to their medically significant venom, Noble False Widows are extremely adaptable and competitive in the wild. Two decades ago, this species was almost unknown in Ireland, the UK or in continental Europe.

We still have much to learn about its genetics, origin, behavior and development. One thing is certain though: this species is here to stay, and we must learn how to live with it.

To help clinicians dealing with cases of spider bites, the research team at NUI Galway has established a DNA database to allow clinicians to confirm the species’ identity using genetic analysis. The researchers are also encouraging members of the public to email [email protected] with details of the situation if they think they may have been bitten.

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Emily Brown

Emily Brown first began delivering important news stories aged just 13, when she launched her career with a paper round. She graduated with a BA Hons in English Language in the Media from Lancaster University, and went on to become a freelance writer and blogger. Emily contributed to The Sunday Times Travel Magazine and Student Problems before becoming a journalist at UNILAD, where she works on breaking news as well as longer form features.

Topics: Science, Britain, Ireland, Now, spider, venom


Clinical Toxicology
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